This invention relates to an ink agitator for use in ink fountains of printing presses.
It is customary to provide a traversing agitator in the ink fountain to mix the ink, to prevent ink skinning, to maintain a uniform distribution of ink along the length of the fountain and, most importantly, to assure that the ink is applied uniformly along the length of the ink fountain roller and there is an adequate supply of ink at the metering nip between the roller and the ink fountain blade.
A feature common to most, if not all, ink agitator devices is a stirring element having a configuration which, when the element is translated longitudinally of the fountain, applies components of force which tend to overcome cavitation of the ink next to the rotating roller and which drive ink positively into the nip between the roller and fountain blade. Most commonly, the ink agitator stirring element is mounted on a carriage which is reciprocated with an electric motor having a gear type speed reducer which drives a closed loop chain running horizontally on sprockets. Means are provided for coupling the carriage to the upper run of the chain to drive the carriage and stirring element in one direction and to uncouple the carriage from the upper run at the desired limit of the traverse and couple it to the lower run for being driven in the opposite direction to the other limit.
Ink agitator elements of various configurations have been devised. A commonly used ink agitator uses a rotating cone shaped element which is positioned in the ink fountain with its axis transverse to the axis of the ink fountain. There is a small clearance between the periphery of the cone and the fountain blade. The apex of the cone is placed as close as possible to the line where the blade becomes nearly tangent to the fountain roller with the objective of assuring that ink will be forced into the nip between the roller and the blade. The cone is attached to a carriage which is driven by a closed loop chain reversibly along the length of the fountain. Typically, a pinion is provided on the cone axis and it engages with a stationary rack so as to impart rotational motion to the cone during its translation. A cone type agitator is described in U.S. Pat. No. 2,849,952 issued on Sept. 2, 1958 to H. W. Gegenheimer. Although the cone shaped ink agitator has been widely used, the motor, speed reducer sprocket and closed looped chain mechanism which is used to translate the ink agitator is complicated and expensive to manufacture. The motor and speed reducer all stand up prominently above the frame which supports the agitator drive mechanism which means that these components can be obstructions to movements of the pressmen when he is cleaning the inking fountain. Moreover, these prior art drive systems do not provide optimum translational speed and translational limit adjustments. The prior art drive mechanisms also use a relatively large number of moving parts which, not only increases manufacturing costs but also increase the need for lubrication and other maintainence procedures.